up

backend/services/cache.py

@@ -0,0 +1,58 @@
+"""磁盘缓存：SQLite 持久化，重启不丢"""
+
+import json
+from datetime import datetime, timedelta
+from typing import Optional
+
+from database import get_connection
+
+
+def get_cache(key: str) -> Optional[str]:
+    """获取缓存，过期或不存在返回 None"""
+    now = datetime.now().isoformat()
+    conn = get_connection()
+    try:
+        row = conn.execute(
+            "SELECT value FROM cache WHERE key = ? AND expires_at > ?",
+            (key, now),
+        ).fetchone()
+        if row:
+            return row["value"]
+        return None
+    finally:
+        conn.close()
+
+
+def set_cache(key: str, value: str, ttl_hours: int = 6):
+    """写入缓存，过期时间 = now + ttl_hours"""
+    expires_at = (datetime.now() + timedelta(hours=ttl_hours)).isoformat()
+    conn = get_connection()
+    try:
+        conn.execute(
+            "INSERT OR REPLACE INTO cache (key, value, expires_at) VALUES (?, ?, ?)",
+            (key, value, expires_at),
+        )
+        conn.commit()
+    finally:
+        conn.close()
+
+
+def del_cache(key: str):
+    """删除指定缓存"""
+    conn = get_connection()
+    try:
+        conn.execute("DELETE FROM cache WHERE key = ?", (key,))
+        conn.commit()
+    finally:
+        conn.close()
+
+
+def clean_expired():
+    """清理已过期的缓存（可在启动时调用一次）"""
+    now = datetime.now().isoformat()
+    conn = get_connection()
+    try:
+        conn.execute("DELETE FROM cache WHERE expires_at <= ?", (now,))
+        conn.commit()
+    finally:
+        conn.close()